A rotatable connector device includes a fixed-side member fixed to a fixed body and a rotatable-side member which is attached to the fixed-side member so as to be relatively rotatable thereto and is rotatable by a rotatable operation tool. In a rotatable connector device provided in a steering wheel part of an automobile, the fixed-side member is fixed to a combination switch as the fixed body, and a steering wheel as the rotatable operation tool is attached to the rotatable-side member so as to be relatively non-rotatable thereto.
In the rotatable connector device provided in the steering wheel part, it is especially necessary that the rotatable-side member rotates leftward and rightward uniformly. For realizing this, the steering wheel needs to be attached to the rotatable-side member rotatable with respect to the fixed-side member in a state where the rotatable-side member is at a neutral position which is not eccentric leftward or rightward with respect to the fixed-side member.
As a rotatable connector device for allowing the steering wheel to be attached in such a manner easily, a device disclosed in Patent Document 1 has been proposed. This rotatable connector device operates as follows. The rotation-direction position of the rotatable-side member, which is set at a neutral position in advance, is provisionally fixed. When a steering wheel is attached to the rotatable connector device in this state, the rotatable-side member is automatically released from the provisional fixed state to provide an appropriate manner of attachment of the steering wheel.
Specifically, the rotatable connector device includes a fixed-side member, the rotatable-side member which is attached to the fixed-side member so as to be relatively rotatable thereto both leftward and rightward and which is rotatable along with the rotation of the steering wheel fit to a fitting hole at the center thereof, and a provisional fixing mechanism for provisionally fixing the rotatable-side member at the neutral position on the fixed-side member. The provisional fixing mechanism has a center hole for receiving a steering column rotatable by the steering wheel, and is fixed to a bottom part of the rotatable-side member so as to be relatively non-rotatable thereto. An engaging part (locking projection 47) of an engaging member (locking body 17) is moved upward by an urging force of a spring member (return spring 18), which is formed of a coil spring built in the provisional fixing mechanism in a state of surrounding the center hole. The engaging part is engaged with an engageable part (engaging part 66) of the fixed-side member to realize provisional fixation. (The reference numerals are those in Patent Document 1; this is applicable to the rest of this section of the specification.)
The engaging part is formed to project outward so as to run through a part of a bearing member (bearing sleeve 16), for receiving a bottom end of the spring member, from inside to the outside so that the engaging part is non-rotatable with respect to the bearing member. A pair of such engaging parts are formed at two positions which are on a straight line while having the center point of the center hole therebetween. The engageable part engageable with such an engaging part is formed at many positions all along the outer periphery of the center hole in the fixed-side member.
A spring contact face of the engaging member that is contactable with a top end of the spring member and an area in the vicinity thereof are formed to have a uniform planar shape.
When the rotatable connector device having such a structure is fixed to a combination switch and then the steering wheel is attached to the rotatable-side member, the engaging member of the provisional fixing mechanism is pushed upward against the urging force of the spring member, and the engaging part and the engageable part are disengaged. As a result, the steering wheel is made rotatable uniformly leftward and rightward.